Ecology Flashcards
Ecology
is the rigorous study of climate and interactions with other species in understanding how these influence the distribution and abundance of organism
Organismal Ecology
how does an organism’s structure, physiology, and behavior affect its survival in the environment
Ex. How do flamingos mate?
what mechanisms are involved in mate selection
Population Ecology
analyses factors that effect population size and how it changes through time
Ex. What environmental factors affect the reproductive rate of flamingos?
Community Ecology
examines how interactions between species, such as predation and competition, affect community structure and organisation
Ex. What factors influence the diversity of species that interact within an area?
Ecosystem Ecology
emphasises energy flow and chemical cycling between organisms and their environments
• Ex. What factors control photosynthetic productivity in this aquatic ecosystem?
Landscape Ecology
focuses on factors controlling exchanges of energy, materials, and organisms across multiple ecosystems
Ex. To what extent do nutrients from terrestrial ecosystems affect organisms in this lake?
Global Ecology
examines how the regional exchange of energy and materials influences the functioning and distribution or organisms across the biosphere
Ex. How do global patterns of air circulation affect global distribution of species?
How does earths climate vary?
Earth’s climate varies by latitude and season
And is changing very rapidly!
climate
the long term prevailing weather conditions in an area
The main driver of organismal distribution
Insolation
is the intensity of sunlight (energy) in a given area during a period of time
What factors determine the climate?
Solar energy ( Insolation)
Seasonality
Water Bodies
Mountains
Where is insolation higher?
highest at equator because we get the most amount of direct sunlight from space
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Higher temps in the tropics evaporate more water, causing warm air masses to flow to the poles
As they move over tropics, condense and release moisture (rain)
Dry air creates deserts (~30°N/S)
Seasonality
The Earth’s tilt toward the sun and annual rotation around the sun causes strong seasonal variations in middle to high latitudes (affects insolation)
Changes day length, solar radiation, temperature
Can cause seasonal shifts in rainfall amounts, wind patterns, ocean currents
Water Bodies
Ocean currents affect climate by heating and cooling overlying air masses
Coastal regions are also generally wetter than intercontinental areas
Supports huge diversity of coniferous rainforests(Giant redwoods and Sitka spruces along West Coast), or fog forests of Newfoundland
How does specific heat capacity moderate climate?
The specific heat capacity of water means water moderates local climates
- On hot days, land is warmer than water and warmer air masses draw in cooler air masses from water to land
- At night, water cools more slowly than land, drawing cooler air from the land away and warming it with the warmer air from water
Mountains
When warm air meets a mountain, the air rises and cools
The windward side receives abundant rainfall as the air moves up the mountains
On the leeward side, air is now cooler and descends, picking up moisture and resulting in a “rain shadow” (drier
Produces the world’s deserts and also Alberta Chinooks
What do mountains also affect?
Also affect sunlight
South-facing slopes in the N. hemisphere receive more sunlight than north-facing slopes, and are thus warmer and drier
Spruce and conifers grow on the cooler north-face and shrubby, drought-resistant plants grow on the south-face
Every 1000m increase in elevation drops the temperature by ~6°C
microclimate
Very fine, localized patterns in climatic conditions
Weather
day to day activity
What factors cause microclimate?
Abiotic–non-living
Biotic-living
Abiotic
–non-living
Chemical and physical attributes
Temperature, light levels, water , nutrients
Biotic
Forest trees moderate climate below them by casting
shade, reducing wind, reducing surface evaporation
Creates a cooler, humid microclimate
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The burning of fossil fuels and deforestation have dramatically changed the Earth’s climate in a directional shift from Earth’s normal climate -> climate change
The burning question becomes then if current global species will be able to adapt to these climatic shifts
What can global climate change affect?
can affect the interactions of life all around Earth (biosphere)
What questions do ecologists ask?
Ecologists ask not only where are organisms found, but also why?
What factor can affect distribution?
Physical location of the land can affect distribution
• Kangaroos in Australia are found no where else on Earth
where are organisms found, but also why?
Maybe it’s because they never had a chance to
disperse
What evidence do ecologists use?
Ecologists can use molecular evidence to unravel evolutionary pasts and historic dispersal routes
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As climate warms, natural range expansion can occur, however abiotic factors can limit how much they expand their ranges
Range expansions can have huge affects
Coyotes expand into new territories, reducing deer populations
Reduced deer populations affect tick populations and reduce the prevalence of Lyme-disease (if humans don’t control coyote populations
Coyotes can also hybridise with wolve “coy-wolf”, ie Eastern coyote
What factors can affect dispersal?
abiotic and biotic
What abiotic factors affect dispersal?
Temperatures, salinity, water levels, sunlight, soil nutrients/composition can also prevent organisms from tolerating and surviving in new environments
fundamental niche
The abiotic factors that permits an organism to survive in an area
Populations
are a group of individuals from the species inhabiting the same general area
Rely on the same resources, are influenced by the same environmental factors, and are likely to interaction and interbreed with each other
Density
is the # individuals per unit area or volume
How are populations described?
Described via boundaries and size (ie # individuals in an area)
What are different methods sued to determine density?
mark-recapture, counting a subset per unit area and extrapolating, counting proxies (tracks, fecal piles, number of nests, etc)
Immigration
influx of new individuals from another population
Emigration
movement of individuals out of a population to
other locations
Dispersion
is the pattern of spacing among individuals
Clumped
aggregate in patches (ie plants and fungi due to soil conditions)
most common
Uniform
evenly spaced (i.e. territorial animals, flocks of birds)
Random
spacing is independent of other individuals (ie dandelions)
What are the different dispersion patterns?
clumped
uniform
random
Demography
is the study of vital statistics of populations and how they change over time
Birth rates
frequency of live offspring born in a population
Death rates
frequency of deaths in a population (ie Mortality rate during a given time frame
When looking at birth and death rates which population do we look at?
Usually just look at females since only females physically produce offspring
survivorship curve
Can represent the survival data as a survivorship curve
Plot of the proportion of individuals in a cohort still alive at each age
What are the different types in a survivorship curve?
Type I – flat at start, low death rates early on
• Typical of large mammals that produce few offspring but high investment in parental care
- Type II – intermediate, constant death over lifespan
- Typical of ground squirrels and small animals
- Type III – sharp death rate at start, declines as aging increases
- Typical of organisms that produce abundant young (fish, plants,fungi etc),and do not provide much for parental car
What tools are used to estimate reproductive rates?
Estimate via direct counts, mark-recapture method
• Estimate with molecular tools
• Skin samples from mother and amplify DNA using genetic markers using PCR
• Then sample young to see how many match the genetic profile of the mother
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Temperature and moisture are main abiotic factors limiting dispersal
Affects biological processes
Cells can rupture if water they contain freeze
Proteins denature in high temperatures
Temperature sets northern limit for many Northern Hemisphere species
• These have evolved adaptations to survive with temperature fluctuations
• Ecotherms have evolved behaviours to adapt to these changes (ie burrowing in mud during the winter)
What are the biotic factors affecting dispersal?
Negative interactions with predators or herbivores can restrict an organism’s ability to survive and reproduce
Absence of food sources or plant pollinators
Presence of pathogens, parasites, or other competing species
Humans
When can populations expand?
Populations have the potential to expand in size when resources are abundant and conditions are ideal
How is population size determined in an ideal environment?
population size is determined by births, immigration, deaths, and emigration
Change in Population =
Births + Immigrants – deaths – emigrants
If we ignore immigration/emigration…
we can represent the change in population (N) over time (t) as the number of births (B) – deaths (D)
B-d=R
Ecologists like to use….
models that describe percapita(per individual). The per capita change in population size (rΔt) represents the contribution that an average member of the population makes to the number of individuals added/subtracted during a time interval
Example of percapita
Ie if a population of 1000 increases by 16 individuals per year, it has a per capita change of 16/1000
If we know the per capita change and the size of the population, we can calculate R
exponential growth
Populations whose members all have access to abundant food and resources grow rapidly, exhibit this growth
What does the graph of an exponential growth look like?
The resulting plot has a “J” shaped curve
• The per capita rate of increase remains constant (and equals r)
• The number of individuals added to the population gets larger and larger per unit time
Give an example of exponential growth:
Population has a constant growth rate of 2 will increase by 40 individuals per unit time but will add 200 individuals when the population size is 100.
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Populations with higher rates of increase (r=1) will grow faster than one with lower rates of increase (r=0.5)
Characteristic of populations that are introduced to new environments or in populations rebounding from a drastic event
Logistic Growth
Environments have limited resources, and as populations increase, the resources decrease
Carrying capacity (K)
is the maximum population size that an environment can sustain
• If a population doesn’t have enough resources, birth rates decrease and the populations decline
Logistic growth models
are sigmoidal, that is the population per capita growth approaches zero as K is d𝑡 𝐾 reached
Describe when N is < > or = to K
When NK, (K-N)/K is close to 0 and per capita growth rate is low
When N=K, the population will stop growing
When N
why does the population growth rate decrease as N approaches K?
- Birth rate decreases
- Death rate increases
- Both birth rate decreases and death rate increases
When are new individuals added to the population? Why
New individuals are added to the population most rapidly during the intermediate population sizes
• Enough breeding individuals available
• Available space and resources still abundant
What are the assumptions of logistic models?
Logistic models have assumptions that do not really fit real biological scenarios
• Assumes populations can adjust instantaneously to increase density by lowering birth rates or raising death rates (there is often a delay)
• Populations will often overshoot carrying capacity temporarily
• Assumes environment doesn’t change (environments always change
biological community
is a group of populations of different species that live close enough to interact
Interspecific interactions
are interactions between different species
Intraspecific interactions ex;
Competition-/- Predation+/- Herbivory+/- Parasitism+/- Mutualism+/+ Commensalism+/0 Altruism (facilitation) +/+ or +/0
What do species interactions influence and How?
Species interactions influence the community composition
Species decline or increase abundance as interactions alter survival or reproductive rates of others
Interactions can also influence evolution of species, changing their morphology, physiology, and behavior
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Kelp forests provide food and shelter for a variety of species
Sea urchins can decimate kelp forests, affecting the other members in the community
Interspecific competition
is a negative ecological interaction
Give examples of Interspecific competition
Individuals of different species compete for limiting resources (resources that are required for growth and development)
Garden weeds compete with planted flowers for soil nutrients and water
Grasshoppers and bison compete for grass to eat
Competitive exclusion
occurs when one species uses the resources more efficiently than the other species
What does Competitive exclusion lead to?
Leads to one species being stronger and more fit (higher reproductive success) than the other species
Eventually causes local elimination of the inferior competitor
What did the study of Paramecium aurelia and P. caudatum show?
G.F. Gause studied Paramecium aurelia and P. caudatum
When grown in culture separately, grew logistically and reached carrying capacity
When grown together, P. caudatum became extinct in the culture since
P. aurelia appeared to have a competitive edge
ecological niche
contains all of the abiotic and biotic resources a species needs to survive
• Can include temperature, size of habitat structures (trees, branches, rocks, etc), food availability, moisture, etc
When can 2 species no coexist?
Two species cannot coexist in the same community if their ecological niches are identical
What allows species to coexist?
Resource partitioning allows species to coexist
Species are able to use some, but not all of the shared niche
Fundamental niches
are the niches potentially occupied by that species
Realised niches
are the portion of the niches a species actually occupies
What did Joseph Connell do?
removed a barnacle species residing beside another one to see if the reason for the stratification was due to interspecific competition
• It was! Chthamalus was able to colonise lower tidal zones when Balanus was removed
exploitation
Any +/- interaction
benefits only one species
Predation
is a +- exploitive interaction where one species (predator) eats another animal (prey)
Animals that eat seeds are also considered predators
What are predators affected by?
Predators are disproportionally affected by humans
We killed off wolves that ate our sheep (still cull wolves in BC)
These have huge affects on the community structure
Describe predator prey relationships
Predator-prey relationships are very interconnected
• Higher prey abundance leads to higher predator abundance and vice versa
What adaptations have prey evolved to reduce predation?
Prey have evolved behavioural, mechanical, and chemical adaptations to help reduce predation
Alarm calls, Mobbing predator (birds attacking predators)
Hiding, fleeing, forming herds/schools
Mechanical spines (porcupines)
Chemical excretions (skunks)
Aposematic (bright) warning colours (poison dart frog)
Cryptic colouration (camouflage)
Batesian mimicry (a palatable species mimics a not-so-good one)
Mullerian mimicry (two or more unpalatable species mimic each other, ie yellow jacket and cuckoo bee)
Herbivory
is an exploitive +/- interaction in which an organism eats a part of a plant or alga
examples of herbivores
Many are large animals such as moose, deer, cows, elephants, bears
Most are invertebrates such as snails, insects, beetles
What can herbivory affect?provide examples
affects the abundance of other species
Desert locusts can swarm and destroy vegetation ,leaving severe economic loss of farmers
Sea urchins can wipe out productive kelp forests into ocean barren
Beavers convert forest-bordered streams into ponds and open meadows, causing shifts in the species of vegetation present
What do herbivores have?
have specialized feeding adaptations
Chemical sensors to distinguish plant species and plant toxicity
Specialized teeth or digestive systems for processing different vegetation types
Parasitism
is an exploitive +/- interaction in which an organism derives nutrients from another organism (host)
~1/3 of all species are believed to be parasites.
Endoparasites
live within the host
• Ex. Tapeworms
Ectoparasites
feed on the external surface • Ex. Ticks and lice
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Some parasites lay their eggs in a host and the larvae hatch and feed on the living host
• Ex.Parasitoid wasps
Some later host behaviour
• Ex. Acanthocephalan worms cause their crustacean hosts to leave protective cover and head into the open to be eaten
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Significantly affect the survival of host populations
• Cause them to be weaker, reduce reproductive output,physical loss of features (ex fur/hair) making them susceptible to the elements
Positive interactions
(+/+ or +/0) occurs when at least one species benefits from the interaction and neither is harmed
Mutualism
is a positive +/+ interaction (not quite symbiosis but can be used synonymously)
Give examples of mutualism
Nitrogen fixing bacteria in legume root nodules
Microorganisms digesting cellulose within the guts of termites and ruminant animals
Mycorrhizae
Endophytic fungi
Photosynthetic algae withing corals
Lichens!
Obligate mutualists
cannot survive on their own and must associate with their mutualistic partner (ex. lichens)
Facultative mutualists
can survive without the mutualism, but benefit greatly from it
• Ie acacia-ant interaction -> will defend the tree in exchange for nectar and protective shelter
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Involve the co-evolution of adaptations in both species, where changes in one species can affect the survival of the other
• Ie Many flowering plants and specific pollinators
Commensalism
is a positive +/0 interaction that only benefits one species but does not harm either
Difficult to document in nature because hard to discern the close association
Often involves on species obtaining food exposed by the other
Does the relationship really not harm or affect the species?
Ie hitchhiking algae on snail shells gain a new place to grow but many actually cause a very slight decrease in reproductive success in the snails….but is it counteracted by the addition of new camouflage?
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Cattle egrets and cowbirds gain abundant food source when bison, cattle, etc disturb and flush out ticks and other insects
Following these animals provides the birds with ample food and little foraging effort
Can affect the cattle. Bison etc too…..birds wil sometimes each the ectoparasites directly off their bodies
Facilitation (altruism)
is a positive +/+ or +/0 interaction where species may not have a direct contact in the symbiosis
Ex Juncus gerardi makes the soil In salt marshes more hospitable, which other plant species can use later
Shades the soil, preventing salt build up due to surface evaporation
Also transports oxygen to the soil
Removing Juncus from the area resulting in a 50% decline in plant species present
Species diversity
number of species present
Relative abundance
the evenness or proportion of each specie
Trophic structure
feeding relationships
species richness
number of species
food chain
the transfer of food energy up trophic levels from its source to its apex
are generally short (4 linkages
shannons index
ρA = relative abundance of species A, etc
ln is the natural logarithm
Higher H means higher diversity
Energetic hypothesis
suggests the length of a food chain is limited by the inefficiency of energy transfer along the chain
trophic efficiency
is the ratio of production of energy at one trophic level to the next lower level
• Ie. The percentage of energy that consumers in trophic level gain and convert into biomass from the total stored energy of the lower level
Why is there energy loss?
Lost via heat from metabolism
Dominant species
are species in a community that has the highest abundance or collectively the highest biomass
• Exert great control over the community
Ex. Sugar maples in eastern North America are dominant, resulting in shading which affects the abiotic conditions of the underlying soil, which in turn affects what other species are present
Could be a result of competitive exclusion or the adaptations to avoid predation/herbivory and disease
Keystone species
are not abundant in the community (and quite often rare) yet exerts a strong control on community structure
• ex. Sea otters are keystone species in kelp forests
They feed on sea urchins, which can eliminate kelp forests
Removal of the otters resulted in overgrazing of the urchins on the kelps, wiping out kelp populations and altering the community structure
Ecosystem engineers
dramatically alter their community by changing the physical environments within the community
Ex beavers building dams and flooding streams and meadows
Ex foxes in the arctic
What controls the biomass of a species?
Top-down control (Trophic cascade model)-
bottom up
Top-down control (Trophic cascade model)-
reducing number of predators increases prey
• ie. Predation limits herbivores, which limits plants, which limits nutrient uptake
Bottom-up control
increase in food, increases higher trophic levels
• ie nutrient levels control plants, which controls herbivores, which controls predators
carbon cycle
Chemical get recycled within the ecosystems
Carbon forms the framework for all of life’s organic molecules
CO2 is used by plants in photosynthesis and converted to sugars that are used by consumers. CO2 is returned to the ecosystem via respiration
Much of the carbon is stored as fossil fuels, soils, sediments in aquatic ecosystems, dissolved in oceans as calcium carbonate, atmospheric CO2 and plant/animal biomass.
Burning of fossil fuels and wood adds more CO2 to the atmosphere, as well as volcanic eruptions. Increased forest fires and peat bog fires also contribute to ever- increasing CO2 levels in the atmosphere
